Rocker arm drive assembly for weaving apparatus



March 26, 1968 MILANI 3,374,632

ROCKER ARM DRIVE ASSEMBLY FOR WEAVING APPARATUS Filed Oct. 20, 1965INVENTOR.

LU/Gl M/LHNI MWWWM W United States Patent 3,374,682 ROCKER ARR I DRIVEASSEMBLY FOR WEAVING APPARATUS Luigi Milani, Vanzaghello Magnago, Milan,Italy, assignor to Brevitex Etablissement pour lExploitation de BrevetsTextiles, Vaduz, Liechtenstein Filed Oct. 20, 1965, Ser. No. 498,917Claims priority, application Italy, Dec. 4, 1964, 26,048/64, Patent743,819 3 Claims. (Cl. 7443) ABSTRACT OF THE DISCLOSURE A drivingmechanism for operating the pawls which, in turn, operate the means forlifting the heddles of a dobbie of a loom, is disclosed as including adriven shaft rotated by the loom main shaft and having secured thereon aplurality of circular bushes. Each bush is operatively associated with arespective knife bearing arm for operating a pawl, and the center ofeach circular bush is offset radially from the axis of the driven shaft.

A plate is operatively associated with each bush and is formed with acircular opening rotatably embracing the associated bush, and each platehas a pivotal connection closely adjacent its circular opening andpivotally connecting the plate to a respective knife bearing arm at apoint spaced from the pivotal mounting of the latter. Each plate thusforms a short crank rod for the associated knife bearing arm, and has anappreciable dwell time at dead center which assures secure engagementbetween its associated knife bearing arm and the associated pawl, fordrawing the pawl, during rotation of the associated bush, withoutappreciable play.

Background of the invention This invention is related to a drive for theoperating levers of the tie rods for the rocker arms that lift thehedclles in the dobbies.

According to the invention, the main object is to realin a device of theabove referred to kind, suitable for obtaining a greater textileproduction, as well as a construction which is simpler and thereforeless costly and more safely efficient, as compared to the known devices.

Known devices are essentially based upon means of kinematictransmission, which are represented by cams deriving their motion fromthe main shaft of the dobbie, and with reference to this lay-out, whichcalls for the use of means for the kinematic transmission to be used forlifting the heddles, said devices are quite slow and consequently theproduction of fabric is also affected. Besides, the use of cams callsfor a rather accelerated wear of the moving elements, which makesnecessary the replacement of said elements and therefore causes thestopping of the dobbie with consequent loss of production.

These and other difficulties are eliminated by the device, realizedaccording to this invention, which is essentially characterized in that,for the drive of heddles, there is provided an eccentric mechanism ofthe rod and crank type, the said device being placed in correspondenceof the forepart of the known arms (i.e. above the pattern-bearingcylinder), so as to drive the heddles by traction (and not by thrust) asin the already known instances, the kinematic linkage for transmittingthe motion from the driven shaft of said device to the shaft of thepattern-bearing cylinder being obtained through at least one pair ofoval or elliptical gears, of ratio equal to 1:1, the first of which isrigidly keyed upon the said driven shaft, while the second gear is usedfor transmitting the motion to a third gear which has the role oftransmitting, through a suitable gear train, with the known ratio 1:8,the rotation of the shaft of the pattern-bearing cylinder.

Owing to the inventive concept now explained, the device realizedaccording to this invention allows also for the abolition of thespringing means used for keeping the followers in continuous contactwith the contour of the driving cams, per se already known, up to nowused in the devices of this kind.

The invention will now be more completely described with reference toone embodiment, being given only as an example and as shown in theenclosed drawing in which:

FIG. 1 shows a schematic elevation, on a reduced scale, exclusivelylimited to the arms with the relevant pawls as well as the operatinglevers of tie rods driven by the device, of a device according to thisinvention; and

FIG. 2 shows, also in elevation, the transmission device for the motionfrom the driven shaft to the shaft of the pattern-bearing cylinder.

With reference to the enclosed drawing, with a there are shown the lowerarms and with b there are shown the upper arms, per se known,respectively fulcrumed in 1 and 2, which arms drive, with their ends3a3b, the relevant knives 4a-4b, respectively the upper and lower ones.The knives 4a4b, fixed upon the arms 3a3b, respectively drive the pawls5a and 5b, being the upper and lower ones, which are fulcrumed at 6 and7 upon the yoke 8, itself pivoted with the follower 9 in the seat 10,formed by the hook 11 of levers c fulcrumed in 12 for operating the tierods (not shown at the drawing) through the relevant arm 13 for loweringthe heddles, said elements being per se known.

According to the invention, each of said arms a and b is driven throughan eccentric mechanism comprising one rod, of which only one shall bedescribed as they are identical, and for the similar elements of eachone the same reference number shall be used, but followed respectivelyby letter a or b respectively if related to arm a or b.

Each rod and crank mechanism is formed by a bush 14a of circular crosssection, having the .role of a crank, as the same is freely slid-ablylodged in a corresponding seat 15a formed in a plate 16a which acts as arod, while upon the bush 14a there is provided one seat 17a, of center0, which is eccentric with reference to center 0', of seat 15a of saidbush 14a, but with parallel axis in order to receive, with a rigidkeying, the shaft 18 which is the driven one, per se known, which isrotatably driven by the main shaft of the loom (not shown in thedrawing). Said rod 16a, like a plate, is pivoted with its head 19a uponone pivot 20a, fixed on a projection 21a formed upon its arm a.

Identically for the second arm b which has a kinematic connection withshaft 18 through a similar bell and crank device, respectively formed bya plate 16b with its relevant eccentric bush 14b, together with otherelements already described for arm a.

In such a way one obtains the operation of pawls 5a and 5b, andtherefore the reciprocating oscillation of levers 0, driving the tierods for lifting the heddles (not shown in the drawing).

The kinematic transmission for transmitting rotation from shaft 18 tothe latter shaft 22 of the pattern-bearing cylinder 23 (not shown in thefigures), is provided through a mechanism, as already said, formed byoval or elliptical gears. To this end (FIG. 2) upon the shaft 18 thereis keyed an oval or elliptical gear 24 meshing with a similar gear 24',but staggered or angularly offset degrees with reference to gear 24. Thesaid gear 24' causes the rotation, through a gear train 25 of shaft 22upon which there is rigidly keyed the gear 26.

The gears now described are designed so that the transmission rat-iobetween shaft 18 and shaft 22 is made equal to 8:11.

With 27 and 28 there are shown the two known ratchets, respectively usedfor driving the rocker arms 2930, also known in themselves, and bothfulcrumed at 31.

With 29' there is shown the end of rocker arm 29 which, when its camloses contact with the relevant ratchet 27, has the function of liftingwith its end 29 the pawl 5a placing the same in an inactive position.

Identically to the former case, with 30' there is shown the end ofrocker arm 30 which, when it loses contact with its ratchet 28, liftswith its end 30' the pawl 5b, placing the same in the inactive position.

In order to simplify, on FIG. 1 there have been shown only two ratchets.

While a specific embodiment of the invention has been shown anddescribed in detail to illustrate the principles of the invention, itwill be understood that the invention may be embodied otherwise withoutdeparting from such principles. 7

What is claimed is:

1. In a dobbie for a loom including heddles, rocker arms for lifting theheddles, tie rods operatively associated with the rockerarms, operatinglevers for the tie rods, pawls operatively associated with the operatinglevers, pivotally mounted knife bearing arms for operating the pawls anda driven shaft driven by the loom main shaft; driving mechanism for saidpawls comprising, in combination, circular bushes secured to rotate withsaid driven shaft and each operatively associated with the respectiveknife bearing arm, the center of each bush being offset radially fromthe axis of said driven shaft; and plates each operatively associatedwith a respective bush and formed with a circular opening rotatablyembracing the associated bush, each plate having a pivotal connectionclosely adjacent its circular opening and pivotally connecting the plateto a respective knife bearing arm at a point spaced from the pivotalmounting of the latter; each plate thus forming a short crank rod forthe associated knife hearing arm, and having an appreciable dwell timeat dead center assuring secure engagement between its associated knifebearing arm and associated pawl for drawing the pawl during rotation ofits associated bush without appreciable play.

2. In adobbie, driving mechanism, as claimed in claim 1, in which eachknife bearing arm is a lever pivoted at one end and bearing a knife atits free end, and having an extension intermediate its ends pivotallyconnected to the associated plate at such pivotal connection of thelatter. 7

3. In a dobbie, driving mechanism, as claimed in claim 1, in which eachplate is oval-shaped in plan with a part of greater diameter formed withsaid circular opening and a part of lesser diameter having said pivotalconnection.

References Cited UNITED STATES PATENTS 7 41,128 '1/1864 Snook 74570X507,016 10/1893 Kuowlton et a1. 74-5-70X 1,826,318 10/1931 Lundgren139'66 2,069,330 2/1937 Rossmann 139-,'66 2,143,236 1/1939 Bi'rk 74--437X 2,781,800 2/1957 Papworth 7443 X FRED C. MATTERN, 111., PrimaryExaminer.

W. S. RATLIFF, Assistant Examiner.

